In recent years, the image recording material is predominated particularly by a material for forming a color image. More specifically, a recording material using an ink jet system, a recording material using a heat-sensitive transfer system, a recording material using an electro-photographic system, a silver halide light-sensitive material using a transfer system, a printing ink, a recording pen and the like are popularly used. Also, a color filter for recording/reproducing a color image is used in an image pick-up element such as CCD of photographing equipment, or in LCD or PDP of display.
In these color image recording materials or color filters, three primary color dyes (dyes or pigments) by a so-called additive or subtractive color mixing method are used for reproducing or recording a full color image, however, a dye having absorption properties capable of realizing a preferred color reproduction region and having fastness capable of enduring various use conditions is not found at present and improvements are keenly demanded.
The ink jet recording method has been abruptly spread and is further growing because the material cost is low, high-speed recording can be obtained, noises are less generated at the recording and color recording is easy.
The ink jet recording method includes a continuous system of continuously jetting out a liquid droplet and an on-demand system of jetting out a liquid droplet according to image information signals, and the ejection system therefor includes a system of ejecting a liquid droplet by applying a pressure using a piezoelectric device, a system of ejecting a liquid droplet by generating bubbles in ink using heat, a system of using an ultrasonic wave, and a system of ejecting a liquid droplet by suction using an electrostatic force.
The ink used for ink jet recording includes an aqueous ink, an oily ink and a solid (fusion-type) ink.
The dye used in such an ink for ink jet recording is required to have good solubility or dispersibility in a solvent, enable high-density recording, provide good (color) hue, have fastness to light, heat and active gas in environment (for example, oxidative gas such as NOx and ozone, and SOx), exhibit excellent resistance against water and chemicals, ensure good fixing property to an image-receiving material and less blurring, give an ink having excellent storability, have no toxicity and high purity and be available at a low cost.
However, it is very difficult to find out a dye satisfying these requirements in a high level. In particular, the dye is strongly demanded to have good cyan (color) hue and fastness to light, humidity and heat and when printed on an image-receiving material having an ink-accepting layer containing a porous white inorganic pigment particle, be resistant against oxidative gas such as ozone in the environment.
Examples of the skeleton (i.e., the basic structure) of the cyan dye used for such an ink for ink jet recording include a phthalocyanine structure, an anthraquinone structure and a triphenylmethane structure. Among these, the phthalocyanine structure is representative.
Representative examples of the phthalocyanine dye which has been reported and is used over the widest range include phthalocyanine derivatives classified into the following (1) to (6).    (1) Copper phthalocyanine-base dyes such as Direct Blue 86 and Direct blue 87 [for example, Cu-Pc-(SO3Na)m: a mixture of m=1 to 4]. In the formula and hereinafter, “Pc” means a phthalocyanine skeleton.    (2) Direct Blue 199 and phthalocyanine-base dyes described in JP-A-62-190273 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”), JP-A-63-28690, JP-A-63-306075, JP-A-63-306076, JP-A-2-131983, JP-A-3-122171, JP-A-3-200883, JP-A-7-138511, etc. [for example, Cu-Pc-(SO3Na)m(SO2NH2)n: a mixture of m+n=1 to 4].    (3) Phthalocyanine-base dyes described in JP-A-63-210175, JP-A-63-37176, JP-A-63-304071, JP-A-5-171085, WO00/08102, etc. [for example, Cu-Pc-(CO2H)m(CONR1R2)n: m+n is an integer of 0 to 4].    (4) Phthalocyanine-base dyes described in JP-A-59-30874, JP-A-1-126381, JP-A-1-190770, JP-A-6-16982, JP-A-7-82499, JP-A-8-34942, JP-A-8-60053, JP-A-8-113745, JP-A-8-310116, JP-A-10-140063, JP-A-10-298463, JP-A-11-29729, JP-A-11-320921, EP-A-173476, EP-A-468649, EP-A-559309, EP-A-596383, German Patent 3,411,476, U.S. Pat. No. 6,086,955, WO99/13009, British Patent Publication 2,341,868A, etc. [for example, Cu-Pc-(SO3H)m(SO2NR1R2)n: m+n is an integer of 0 to 4 and m≠0 (i.e., m is not 0)].    (5) Phthalocyanine-base dyes described in JP-A-60-208365, JP-A-61-2772, JP-A-6-57653, JP-A-8-60052, JP-A-8-295819, JP-A-10-130517, JP-A-11-72614, Japanese Unexamined Published International Application Nos. 11-515047 and 11-515048, EP-A-196901, WO95/29208, WO98/49239, WO98/49240, WO99/50363, WO99/67334, etc. [for example, Cu-Pc-(SO3H)l(SO2NH2)m(SO2NR1R2)n: l+m+n is an integer of 0 to 4].    (6) Phthalocyanine-base dyes described in JP-A-59-22967, JP-A-61-185576, JP-A-1-95093, JP-A-3-195783, EP-A-649881, WO00/08101, WO00/08103, etc. [for example, Cu-Pc-(SO2NR1R2)n: n is an integer of 1 to 5].
Phthalocyanine-base dyes widely used in general at present, represented by Direct Blue 87 and Direct Blue 199 and described in those patent publications, are excellent in the light fastness as compared with magenta and yellow dyes, however, are disadvantageously liable to cause a problem ascribable to the solubility of dye. For example, on great occasions, dissolution failure occurs at the production to cause a production trouble or insoluble matters precipitate during storage or on use of the product to bring about a problem. Particularly, in the ink jet recording described above, clogging of printing head or ejection failure is caused by the precipitation of dye and this gives rise to a problem of serious deterioration of the printed image.
Furthermore, discoloration readily occurs due to oxidative gases such as ozone, which are often taken as a problem also from an environmental issue, and this causes a large problem of great reduction in the printing density.
At present, the field using the ink jet recording is abruptly expanding and if this recording system is more widely used in home, SOHO, business and the like, the dye or ink composition is exposed to various use conditions or use environments, as a result, the case of generating a trouble ascribable to solubility failure of the cyan dye or causing a problem of discoloration of the printed image on exposure to light or active gas in the environment increases. To cope with this, a dye and an ink composition particularly having good (color) hue, excellent light fastness and high resistance against active gases (for example, oxidative gas such as NOx and ozone, and SOx) in the environment are more strongly demanded.
However, it is very difficult to find out a phthalocyanine dye and an ink containing the dye, which can satisfy these requirements in a high level.
The phthalocyanine dyes imparted with ozone gas resistance are heretofore disclosed, for example, in JP-A-3-103484, JP-A-4-39365 and JP-A-2000-303009, however, none of these dyes have succeeded in satisfying both the (color) hue and the fastness to light and oxidative gas. Particularly, a case of reporting the property of dye as an index for the ozone gas resistance is heretofore not known.
In general, the phthalocyanine dye (compound) is produced by sulfonating an unsubstituted phthalocyanine compound and in the case of using it as a water-soluble dye, an alkali metal salt of the sulfonated compound, such as sodium salt, is used as it is, and in the case of deriving an oil-soluble dye, a dye synthesized after sulfonation, by sulfonyl chloridation and amidation reactions can be used as described in WO00/17275, 00/08103, 00/08101 and 98/41853 and JP-A-10-36471.
In this case, sulfonation can take place at any site of the phthalocyanine nucleus and the number of sites sulfonated is difficult to control. Accordingly, when a sulfo group is introduced under such reaction conditions, the site and number of sulfo groups introduced into the product cannot be specified and a mixture of those different in the number of substituents or in the substitution site inevitably results.
In this mixture, a component having low solubility, for example, a component where the number of sulfonated site on the phthalocyanine nucleus is 0 or 1, is mixed and the solubility is liable to be insufficient for use as a water-soluble dye. Thus, the improvement of solubility is demanded.
Problems to be Solved by the Invention:
The present invention has been made to solve those problems in conventional techniques and achieve the following objects. That is, a first object of the present invention is to provide a novel dye mixture having absorption properties with excellent color reproduction as a dye for three primary colors, having sufficiently high fastness to light, heat, humidity and active gas in the environment, and having excellent solubility.
A second object of the present invention is to provide a phthalocyanine dye mixture having excellent ink storage stability and recoverability from clogging, giving good (color) hue, enabling the formation of an image having high fastness to light and active gases in the environment, particularly against ozone gas, and ensuring high recording stability even when used in various environmental conditions, which is particularly effective for use in an ink, an ink for ink jet recording, an ink set for ink jet recording comprising the ink for ink jet recording, an ink jet recording method using the ink for ink jet recording, and a container or the like for housing the ink for ink jet recording.
Means to Solve the Problems:
As a result of extensive investigations on phthalo-cyanine dyes having good (color) hue and solubility and having high fastness to light and gas (particularly ozone gas), the present inventors have found that the above-described objects can be attained by a phthalocyanine dye mixture having a specific structure which has been heretofore not known.
Disclosure of the Invention:
The present invention has been accomplished based on this finding. The means for solving the problems is as follows.
That is,
<1> a dye mixture comprising a plurality of different dyes represented by the following formula (I):
wherein M represents a hydrogen atom, a metal atom or an oxide, hydroxide or halide thereof; Pc represents a (k+l+m+n)-valent phthalocyanine nucleus represented by formula (II); X1, X2, X3 and X4 each independently represents a substituent selected from the group consisting of —SO—R1, —SO2—R1, —SO2NR2R3, —CONR2R3, —CO2—R1 and CO—R1 and at least one substituent represented by X1, at least one substituent represented by X2, at least one substituent represented by X3 and at least one substituent represented by X4 are present in respective rings of four benzene rings {A, B, C and D in formula (II)} of the phthalocyanine nucleus, provided that the case where X1, X2, X3 and X4 all are the same is excluded and at least one of X1, X2, X3 and X4 has an ionic hydrophilic group as a substituent; R1 represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group or a substituted or unsubstituted heterocyclic group; R2 represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group or a substituted or unsubstituted heterocyclic group; R3 represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group or a substituted or unsubstituted heterocyclic group; k, l, m and n represent an integer of 0<k<8, an integer of 0<1<8, an integer of 0≦m<8 and an integer of 0≦n<8, provided that k and/or l and/or m and/or n each independently represents a number satisfying 4≦k+l+m+n≦8; and Y1, Y2, Y3, Y4, Y5, Y6, Y7 and Y8 each independently represents a hydrogen atom and/or a monovalent substituent and these monovalent substituents each may further have a substituent;
<2> the dye mixture as described in <1>, wherein the phthalocyanine nucleus represented by formula (II) is represented by the following formula (III):

<3> the dye mixture as described in <1>, wherein in the dye represented by formula (I), X1, X2, X3 and X4 each independently represents a substituent selected from the group consisting of —SO—R1, —SO2—R1 and —SO2NR2R3, and at least one substituent represented by X1, at least one substituent represented by X2, at least one substituent represented by X3 and at least one substituent represented by X4 are present in respective rings of four benzene rings {A, B, C and D in formula (II) or (III)} of the phthalocyanine nucleus;
<4> the dye mixture as described in <1>, wherein the dye represented by formula (I) is represented by the following formula (IV):
wherein M represents a hydrogen atom, a metal atom or an oxide, hydroxide or halide thereof; Pc represents a (k+l)-valent phthalocyanine nucleus represented by formula (III); X1 and X2 each independently represents a substituent selected from the group consisting of —SO—R1, —SO2—R1 and —SO2NR2R3 and at least one substituent represented by X1 and at least one substituent represented by X2 are present in respective rings of four benzene rings {A, B, C and D in formula (III)} of the phthalocyanine nucleus, provided that X1 and X2 are not the same and at least one of X1 and X2 has an ionic hydrophilic group as a substituent; R1 represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group or a substituted or unsubstituted heterocyclic group; R2 represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group or a substituted or unsubstituted heterocyclic group; R3 represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group or a substituted or unsubstituted heterocyclic group; k and l represent an integer of 0<k<8 and an integer of 0<l<8, provided that k and/or l each independently represents a number satisfying 4≦k+l≦8;
<5> the dye mixture as described in <1>, wherein in formulae (I) and (II), at least one group of X1 to X4 and Y1 to Y8 has at least one asymmetric carbon;
<6> an ink comprising the dye mixture described in any one of <1> to <4>;
<7> an ink as described in <6>, which is used as an ink for ink jet recording;
<8> an ink jet recording method comprising forming an image using the ink described in <7> on an image-receiving material comprising a support having thereon an ink image-receiving layer containing a white inorganic pigment particle; and
<9> a method for improving ozone resistance of a colored image material, comprising forming an image using the ink described in <7>.